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  1. Qt
  2. QTBUG-901

Influence JPEG color sub sampling

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Details

    • Suggestion
    • Resolution: Out of scope
    • P3: Somewhat important
    • Some future release
    • 4.3.0
    • GUI: Painting
    • None

    Description

      In order to change the color sub sampling in JPEG it is necessary to patch the qjpeghandler.cpp file, but it is hard to communicate from QImageWriter to turn it on and off.

      The method setOption ( ImageOption option, const QVariant & value ) of QImageIOHandler should also be in QImageWriter and an additional option "subSampling" to set

      cinfo.comp_info[0].v_samp_factor=subSampling;
      cinfo.comp_info[0].h_samp_factor=subSampling;
      in the write_jpeg_image function.

      Other tools like ImageMagick allow this manipulation of this parameter.

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            rodal Samuel Rødal
            sanonymous Nokia Qt Support (Inactive)
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              Resolved:

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